# Send to only OTEL collector: Authentication failed for https://api.smith.langchain.com/runs/multipart. HTTPError('401 Client Error: Unauthorized for url: https://api.smith.langchain.com/runs/multipart'
**URL:** https://forum.langchain.com/t/send-to-only-otel-collector-authentication-failed-for-https-api-smith-langchain-com-runs-multipart-httperror-401-client-error-unauthorized-for-url-https-api-smith-langchain-com-runs-multipart/2185
**Category:** Observability & Evals
**Created:** [November 13, 2025, 7:09am UTC](https://forum.langchain.com/t/send-to-only-otel-collector-authentication-failed-for-https-api-smith-langchain-com-runs-multipart-httperror-401-client-error-unauthorized-for-url-https-api-smith-langchain-com-runs-multipart/2185 "2025-11-13T07:09:21Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@adam.gardner](https://forum.langchain.com/u/adam.gardner)
#### Post date: [November 13, 2025, 7:09am UTC](https://forum.langchain.com/t/send-to-only-otel-collector-authentication-failed-for-https-api-smith-langchain-com-runs-multipart-httperror-401-client-error-unauthorized-for-url-https-api-smith-langchain-com-runs-multipart/2185/1 "2025-11-13T07:09:21Z")
Hi all, I want to send data **only** to an OpenTelemetry collector.
I can see the data hitting the collector, so that works, but how do I prevent the `401` code as it’s also trying to export to `https://api.smith.langchain.com/runs/multipart`
```auto
set OPENAI_API_BASE=https://my.endpoint.com/api/.../v1
set OPENAI_API_KEY=REDACTED
set LANGSMITH_TRACING=true
set LANGSMITH_OTEL_ENABLED=true
set OTEL_SERVICE_NAME=langchain
set OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318
python app.py
```
Where `app.py` is just something basic:
```auto
from langchain.agents import create_agent
def get_weather(city: str) -> str:
"""Get weather for a given city."""
return f"It's always sunny in {city}!"
agent = create_agent(
model="gpt-4o",
tools=[get_weather],
system_prompt="You are a helpful assistant",
)
# Run the agent
output = agent.invoke(
{"messages": [{"role": "user", "content": "what is the weather in sf"}]}
)
print(output)
```
---
### Author:  [@angus](https://forum.langchain.com/u/angus)
#### Post date: [November 13, 2025, 5:53pm UTC](https://forum.langchain.com/t/send-to-only-otel-collector-authentication-failed-for-https-api-smith-langchain-com-runs-multipart-httperror-401-client-error-unauthorized-for-url-https-api-smith-langchain-com-runs-multipart/2185/2 "2025-11-13T17:53:41Z")
@adam.gardner Hybrid tracing is the default in LangSmith version **≥ 0.4.1**.
To send traces **only** to your OTEL endpoint, set: **`LANGSMITH_OTEL_ONLY="true"`** (Recommendation: use **langsmith ≥ 0.4.25**.)
> **[Trace with OpenTelemetry - Docs by LangChain](https://docs.langchain.com/langsmith/trace-with-opentelemetry#configure-alternate-otlp-endpoints)**